Hydrocarbon drilling systems utilize drilling fluid or mud for drilling a wellbore in a subterranean earthen formation. In some applications, drilling systems include a blowout preventer (BOP) configured to control the inlet and outlet of fluid from the wellbore, and particularly, to confine well fluid in the wellbore in response to a “kick” or rapid influx of formation fluid into the wellbore. An individual BOP stack may include both ram BOPs and annular BOPs. Annular BOPs are configured to close or seal against the outer surface of a drill string extending through the BOP stack.
In some applications, annular BOPs include a hydraulic assembly or package for actuating between an open position allowing for fluid flow in an annulus disposed between the drill string and the annular BOP, and a closed position restricting fluid flow through the annulus. Particularly, the hydraulic package may include an annular packer comprising an elastomeric material that is urged into sealing engagement with the drill string. In some applications, the annular BOP includes an upper housing or top for housing the packer, where the top is releasably coupled to a lower housing to allow for the installation of the hydraulic package therein. In those applications, the annular BOP may include a connection assembly for releasably coupling the top to the lower housing, where the connection assembly is configured to transmit loads applied to the top by the packer, when actuated, to the lower housing.